Precise indexing chuck



Pll 7, 1942 y H. w. EBERHARDT 2,278,651

PRECISE INDEXING CHUCK Filed May 29, 1940 5 Sheets-Sheet l PI' 7 1942- H. EBERHARDT A 2,278,651;

PRECISE INDEXING CHUCK Filed May 29, 1940 3 Sheets-Sheet 2 April 7, 1942. H. -w. EBERHARDT PRECIS INDEXING CHUCK I Filed May 29, 1940 s sheets-sheet 5 /RMHN WEBERHARD Patented Apr. 7, 1942 UNITED STATES PATENT OFFICE PRECISE INDIEXING CHUCK Herman lW. Eberhardt, Paterson, N. J. l Application May A2,9, 1940, Serial No. 337,874

9 Claims.

This invention relates to machine tools, and particularly to a chuck for holding a workpiece Within a rotating machine .such as a lathe.

An object of the invention is to provide la lathe chuck which will accurately retain a rotating workpiece in alignment with the axis of rotation of the lathe, and wherein the angular position of the workpiece with respect to the cutting tools of the lathe may be changed .and accurately retained in the altered angular position.

Another object of .the invention is to lprovide Va workpiece holding chuck of such a construction that precise control is maintained over the angle of index of the workpiece with respect to the cutting tools of the lathe and to permit a plurality of these angular positions of the workpiece so that a plurality of operations may be performed upon the piece at definite angular relations with respect to each other.

A further object is to provide a work holding tion of the lathe in order to make the two axes f coincide, and to provide means whereby the workpiece retained in .the chuck may have the axis of rotation thereof aligned with the axis of rotation of the chuck.

A further object of the invention is to provide a lathe chuck, or Work holding chuck, which will accurately retain a rotating workpiece in alignment with the axis of rotation of a lathe and wherein clamping arms are provided upon the chuck which are adjustable to permit clamping of the workpiece between the arms.

Another object of the invention is to provide a work holding chuck having an indexing plate whereby work may be positioned axially about the axis of the plate, and wherein means are provided to lock the indexing plate in position upon its axis.

It is a still further object of the invention to provide a work holding chuck having an indexing plate and means to support a wo-rk element with respect to the indexing plate, and to provide means for simultaneously coordinating movement of an engaging means for the indexing plate and a locking means therefore to cause simultan'eous positioning andlocking of' the indexing plate.

Further objectives and advantages will be apparent from the following description and a reading of the drawings.

In the drawings:

Figure .l is a top plan view of a lathe incorporating the chuck of this invention;

Figure 2 is a cross-sectional View taken along line 2-2 .of Figure l wherein the chuck is shown in cross-,section while the lathe parts are in elevation;

Figure 3 is a cross-sectional view showing a means for adjusting the chuck with respect to the face plate vof a lathe;

Figure 4 is an elevational View of the chuck and face plate looking in the direction of line 4--4 of `Figure l.

Figure 5 isa perspective view showing the essential parts of the indexing plate, partially in cross-section;

Figure 6 is a cross-sectional View of the workpiece retaining device and shows means for adjusting the workpiece with respect to the retaining device.;

Figure 7 `is a partial cross-sectional View taken along line 'l--l :of Figure 2.

Figure 8 is a cross-sectional View of a modied arrangement of the work holding chuck showing means to adjust the work holding arms and means to lock the indexing plate in position;

Figure 9 is a plan view partially in cross-section taken `along line 9-9 of Figure 8;

Figure ,l0 is a `cross-sectional View of the locking means for the indexing plate taken along line Ill-I0 of Figure 9.

In general, the device of 'this invention consists of a chuck which `is adapted to be mounted upon a face plate of a lathe. The face plate is in turn positioned upon the live center extending from the head stock of the iathe and .in which suitable mechanism is provided for rotating the live center and thus the face plate and the chuck. When turning articles upon which a plurality of operations are performed, and where the operations to be performed are to be displaced angularly around the circumference of the article, difficulty has arisen in accurately indexing an article yso that successive articles machined would have the exact same angularity upon the various surfaces. This is particularly true under circumstances that have required the articles be removed from the machine some time during its Vprocess of manufacture and ybereturned to the machine for iini'shing. When removing the machine tool devices of former practice and replacing them upon a machine the precise position assumed by the device upon replacing the same upon the machine will not be the same as the former position.

The device of this invention is adapted to be mounted upon a fac'e plate positioned upon the lathe. To align the chuck upon the face plate, accurately machined surfaces are provided against which micrometer indicating attachments can abut in order to determine the exact rotational center of the chuck and the exact plane of operation of the chuck at 90 from the axis of rotation of the chuck, whereby the chuck will be positioned accurately upon the face plate so that the centers of rotation of the face plate and chuck will coincide.

The chuck of this invention also is arranged to precisely and accurately index a work element retained in the chuck with respect to the working tools of the lathe in order to machine various surfaces of the workpiece at precise angles.

In this invention the chuck is shown in operation upon a lathe ID. The lathe bed I2 is provided with the ways I3, upon the upper surface thereof, upon which a tail stock (not shown) is positioned in order to slide to and fro along ways I3. Positioned upon the tail stock is a turret I4 wherein one or more working tools I4a may be secured for working upon a workpiece positioned in the lathe. A carriage I5 is mounted upon the ways I3 and is adapted to be moved longitudinally along ways I3 by means of a cross feed rod (not shown) through any of the wellknown driving connections between a cross rod and a carriage mechanism. An apron I6 depends from the front portion of the carriage I5 and has mounted thereon suitable controls for operation of the carriage. The controls may consist of a hand wheel I1 which engages the cross feed rod (not shown) for moving the carriage I5 longitudinally along the ways I3. A carriage control lever I8 may also be provided for starting and stopping the operation of the carriage I5. A head, stock I9 is positioned upon the bed of the lathe and is provided with suitable mechanism for driving the live center of the lathe. The turret I4 which is mounted upon the tail stock, which in turn is carried by the Ways I3 of the lathe, is connected by conventional driving means with the operating mechanism of the lathe in order to advance and retract the turret, and the tools carried thereby with respect to the work carried upon the live center of the lathe. A cross slide is mounted, upon the carriage I5 and is adapted to be moved to and fro transversely of the carriage I5 upon the ways 2I by means of thev cross feed screw 22. A compound tool rest 23 is carried upon the cross slide 20 and is provided with the usual tool post 24. A binder screw 25 is provided upon the tool post 24 for securing the tool 26 to the post 24 and the post to the compound tool rest 23.

A face plate 38 is positioned upon the live center extending from the head stock I9 in any of the Well-known manners such as by screw threading the face plate 30 upon the live center. The face plate 38 is provided with a flat planar surface 3| which under all normal circumstances Would be at right angles to the axis of rotation of the face plate. A plurality of slots 32 extend radially from near the center of the face plate 30 and provide means through which bolts 33 may extend in order to engage or secure a Work element to the planar surface 3|, whereby the element thus secured to the face plate will rotate in the same axis as the face plate.

In this invention a chuck 35 is provided with a planar surface 36 which is adapted to abut the planar surface 3| of the face plate 30. The bolts 33, extending through the face plate 3U extend into threaded engagement with the threaded openings 31 provided in the circular base 38 of the chuck 35 thereby securing the chuck 35 to the face plate 3D. A groove 39 is cut in the edge surface 49 of the base 38 in such a manner that the bottom face of the groove 39 is in concentric relation with the axis of rotation of the base 38. In the exposed face surface 4I of the circular .Y base 38 there is provided a groove 42 which forms an annular groove near the outer edge portion of the face surface. The bottom face of this groove 42 is a finished surface so that it will be in alignment in a plane at right angles to the axis of rotation of the base 38. The function of the grooves 39 and 42 will be hereinafter more fully described.

Extending from the base 33 are two arms 43 and 44. These arms extend vertically from the base in planar alignment and are positioned parallel with respect to each other. The arm 44 is provided with a work securing member 45 Which is pivotally mounted in the bearing 46 positioned in the arm 44. A threaded screw member 41 having an enlarged head 48 is in threaded engagement with the work securing member. The enlarged head portion 48 of the screw threaded member 41 abuts a shoulder 49 on the arm 44. The work securing member 45 is also provided with a shoulder 5 which abuts the arm 44, 'I'he work `securing member 45 is thus retained n a pivotal position upon the arm 44 by means of the shoulders 49 and 50.

An indexing plate 6I! is pivotally mounted upon the arm 43 and has the axis thereof in alignment with the axis of the work securing member 45. The indexing plate 66 consists of a cylinder 6I having an annular groove 62 about'J the midportion thereof, thereby providing a lower shoulder 63 and an upper shoulder 64. The arm 43 is provided with a bearing 65 which is of the split bearing type consisting of two sections 66 and 61. The section 66 of the bearing 65 is integral with the arm 43 while the section 61 is bolted to the section 66 by means of the bolts 68 whereby a full bearing is provided in the annular groove 62 of the indexing plate 60.

The indexing plate has a plurality of radially extending passageways 10. These passageways radiate from the axis of rotation of the indexing plate 6I) and may be bored within the indexing plate 6I) at any suitable angle, the angle being determined by the angularity required by the various indexing positions of the indexing plate 6D. These passages 18 are accurately machined to a uniform size so that when a plunger 1I engages one of the passageways 1I] a close sliding t will result between the plunger 1I and the passage 16 since the plunger 1I has also been machined to close limits on the external diameter thereof. The plunger 1I extends into a bored passage 12 in the arm 43. This passage 12 is also machined to accurate limits so that the plunger 1I will slide in close engagement with the walls of the passage 12. A portion of the plunger 1I provides a gear rack 13 which is adapted to engage a gear segment 14 pivotally mounted upon a pin 15. The rack 13 and the gear segment 14 provide means whereby the plunger 1I may be advanced into one of the passages '|10 in 4the 'indexing .plate 60, 4or be retracted therefrom. The .gear segment T4 may be operated manually to .advance or retract the plunger 1| with respect to the indexing plate 60 to permit manual indexing of the plate y60, or automatic means could beprovided for this operation. A tension vspring 14al tends to retain the gear segment 14 and the plunger 1| vin engaging position in the indexing plate B0. A set screw `|6 is in threaded engagement with an opening Jl in the arm 43, the end of which iis in engagement with the undercut portion 18 of the plunger 'H. The undercut portion 'I8 of the plunger 1| in cooperation with the set vscrew 1-3 limits the travel of the plunger 1|, and also prevents the plunger Ylrorn sliding out of the passage vl2 and through .the indexing plate A|50. Should it occur that a passagel extends transversely through the indexing plate 60.

The indexing plate 60 .and the workpiece retaining member 45 `are provided with the female halves of a dovetail slot 80 and 8|, respectively. Adapter plates 82 and 83 are provided with the male halves 84 and 85 of the dovetail joints 88 and 8|, respectively. These adapter plates 82 and l83 are secured to the workpiece 90 by any suitable means, the method of fastening the adapter plates 82 and 83 to the workpiece 90 isdetermined by the shape and size of the workpiece 90. As `disclosed in Figure 2, the method of attaching a workpiece 90 to the adapter plates B2 .and S3 :consists of -extending a bolt 9| between the adapter plates 82 and 83 and causing the bolt to be in threaded engagement with the adapter plate 83 whereby the workpiece 90 is clamped between the adapter plates. To insure that the workpiece will not rotate with respect to the adapter plates a locating pin 922 extends into the workpiece 90 and locates the plate on the Work.

The male halves `84 and85 of the dovetail joint extend into the female halves 80 and 8| of the dovetail joint whereby the adapter plates 82 and 83 of the workpiece 90 is positioned between the workpiece retaining member 45 and the indexing plate 60. The cooperating portions of lthe dovetail joint between the adapter plates and the work securing member 4'5 and the indexing plate 8 provide means whereby the adapter plates 82 and 8.3 may be slid transverse to the axis of rotation .of the chuck 35 in order to align the axis of rotation of the workpiece V8i) with the axis of rotation of the chuck 35. After the alignment of the rotational axes cf the workpiece 90 and the chuck 35 have been established the adapter lplates are secured into position to prevent misalignment of the axes.

The method of securing the adapter plates to the rwork supporting elements may be of any suitable type. However, I have shown an adjustable device in Figure 6 for aligning the axes of the workpiece 90 and the chuck 35. In this arrangement, which is the same for both the indexing plate 60 `and the work securing element, a gib extends transversely through the indexing plate 18 and a similar gib extends through the member 45 in planaralignment with the male halves 84 and 85 of the dovetail joints in the indexing plate B0 and the work securing member 45. The gib |00 is provided with a tapered face which cooperates with a correspondingly tapered face on the end of the male half of the dovetail joint 84 as at IGI. Retaining screws |02 and |03 are provided at opposite ends of the gib .|00 to locate the gib |00 transversely within the 84 :of the dovetail joint. These 1set screws are provided Ywith tapered .ends |:05 and |07 which are adapted to engage the :slots |08 and k|09 positioned in the side Walls of the rmale half 84 of the dovetail joint. The set screws |04 and |05 bind against the `walls 'of `the slots .|08 and |00, respectively, 'to force the male half 84 of the dovetail joint into an engagement with the taper on the gib as indicated at |0|.

It is thus seen that VI have provided a device for adjusting the axis of rotation of the work-- .piece with respect tothe axis of rotation of the workpiece retaining member 45 and the indexing plate '60 whereby the two axes could :be made to'concide. If the axis of rotation of the work element 90 and the axis of rotation of the work retaining members 45 and 80 coincide, the workpiece 90 will be on the axis `of rotation of the circular base 38. In order to align the axes of rotation of the base 3B and the face plate 30 the base 38 may be shifted upon the face plate 30 until the two axes coincide. At which time the bolts 433 will be tightened in order to .retain the base 38 in position upon the face plate.

In order to check the accuracy of thealignment of the chuck 35 with its base 38 upon the face plate 30 the grooves l39 and 42, heretofore described have been provided in the Iedge surface 40 and the face surface 4|, respectively, of the base 38. The groove 38 has its nished bottom face concentric with `the normal axis of rotation of the chuck 35 with its base V38. This groove provides a true running surface about the axis of rotation of the base 38 against which a micrometer indicating attachment can .abut `and Y a direct reading vbe taken vof the rdegree =of misalignment of the axis of -rotation of the base with respect to the true axis of rotation ofthe face plate and thus of the lathe. If the yaxis of rotation of the base 438 should be out of alignment with the axis of rotation of `the face plate and the lathe the bolts 33 can be loosened whereby the base 3B can fbe shifted Ato bring the axis of rotation into exact coincidence. While vthe axis of rotation ofthe base 38 and face plate 30 and thus the live spindle of the lathe may coincide, yet there is a possibility that the two axes may be angularly displaced. To check the angular displacement of the axis of rotation of the base 38 with respect to the axis of rotation of the face plate 30 the groove 42 is provided. This groove 42 has the bottom face thereof y1inished in a plane at exact right yangles to the true axis of rotation of the rotation of the kbase 38, so that when a micrometer indicating instrument abuts the bottom face of this groove the indicator will indicate the exact angular displacement between the axes vof rotation of the base 38 andv -face plate 30. To correct'` the angular displacement of these axes, a plurality of adjusting bolts ||01can be provided and spaced circumferentially in the face plate 30. These bolts 0 bear upon the yplanar face 36 -of the base 38 whereb'sr tightening of these lbolts may angularly displace the base 38 with respect to the face plate 130 in order to correct the angular displacement therebetween. The bolts 33 lare then tightened to retain the setting.

When the chuck 35 is to be used for holding a workpiece whereupon a plurality ofoperations are to be performed angularly displaced circumierentially-around the workpiece the chuck 35 is positioned upon the faceplate 30 and retained thereto by means of the bolts 33. A micrometer indicating attachment is positioned adjacent the slot 39 in the base 38 and has a protruding end thereof in engagement with the bottom face of the slot 39 as indicated at ||5, see Figure l. The chuck may then be rotated and the indicating attachment ||5 will show the degree of rotational displacement of the axes between the chuck 35 and the face plate 30. A similar micrometer indicating attachment H6, see Figure l, is positioned so that the protruding end thereof will extend into the slot 42 and `abut the bottom face of the slot 42. This instrument ||6 will indicate the angular displacement between the chuck 35 and the face plate 30. The retaining bolts 33 and the adjusting bolts ||0 may be loosened or tightened to permit shifting of the base 38 of the chuck 35 until both the rotational and the angular misplacement of the axes between the chuck 35 and the face plate has been corrected. The chuck 35 will thus be on the exact rotational center of the live spindle extending from the head stock |9. The workpiece 90 with its adapter plates 82 and 83 may then be positioned within the workpiece retaining member 45 and the indexing plate 60. The axis of rotation of the workpiece 90 may then be adjusted in parallel relation with the axis of rotation of the chuck by means of the adjustable arrangement provided by the gib |00 and the set screws |04 and |05 to shift the axis of rotation of the workpiece 90 until it coincides with the axis of rotation of the chuck 35. The workpiece 90 is now centered with respect to a true axis of rotation of the live spindle extending from the head stock I9. The indexing plate has been previously prepared with the proper number of indexing passages 10 spaced at the proper angles through which the workpiece is to be indexed circumferentially while in position in the lathe. After one or more operations have been performed upon any one portion of the workpiece 90 the gear segment 14 is rotated to cause the rack 13 in the plunger 1| to retract the plunger from its passage 10 in the indexing plate 60, whereby the indexing plate may then be manually or automatically rotated to its next indexing position wherein the plunger 1I will again advance into the next successive proper passage, either automatically or manually, to position the workpiece 90 with respect to the cutting tools and the lathe.

It is obvious that the split bearing 65 can also be used as a means for clamping the indexing plate in position about its axis. After the plunger 1| has been extended into one of the passageways 10 to index the plate 60 about its axis and thus index the workpiece 90 to its next successive position, the split bearing 65 can have the portion 61 clamped upon the bearing throat of the indexing plate 60. The bolt 68 extending through the portion 61 of the split bearing 65 threadedly engages the portion 66, which is a part of the arm 43. It is seen that upon tightening the bolt 68 through the portion 66 of the split bearing 65, the portion 61 will be clamped upon the bearing throat of the indexing plate 60, thereby preventing the indexing plate from rotation about its axis while working upon the workpiece 90, thus relieving the plunger 1| of' shearing strain.

In the modification disclosed in Figures 8 to 10, inclusive, the chuck consists oi a circular base |26 which is mounted upon a face plate by means of bolts 33 in a manner similar to that disclosed with regard to the chuck 35. The The face plate 30 is carried upon the spindle of the lathe extending from the head stock |9 thereof. The circular base |26 is provided with a groove |21 within the edge surface thereof, and provides means whereby the concentricity of the chuck |25 may be checked against the axis of rotation of the spindle of the lathe. A groove |28 is provided within the face surface of the base |26 and is arranged as an annular ring near the outer edge of the circular base, and provides means for checking the angular displacement of the chuck with respect to the axis of rotation of the spindle of the lathe. These grooves thus function in the same manner as the grooves 39 and 42 of the chuck 35.

The base |26 has a dovetail slot |29 cut therein and arranged across the true diameter of the base. Arms |30 and |3| extend vertically from the base |26 and are arranged parallel with respect to each other and in planar alignment. The arms |30 and |3| are provided upon one end thereof with a dovetail shaped extending portion |32. This portion |32 cooperates with the dovetail shaped groove |29 in the base |26 to provide means for mounting the arms |30 and |3| upon the base |26 in sliding relation therewith.

A screw |33 extends through the male portion of the dovetail joints of the arms |30 and |3I, and in threaded engagement therewith. One end of the screw |33 is provided with a left-hand thread while the opposite end is provided with a right-hand thread so that when the screw is rotated Within its supporting bearing blocks |34, the arms |30 and |3| will be caused to move inwardly toward the central rotational axis of the chuck |25 or away therefrom. The arms |30 and |3| move simultaneously upon rotation of the screw |33 so that a work element, indicated at 90, may be clamped between extending portions of the arms |30 and |3| upon the rotational center of the chuck |25. The ends of the screw may be provided with a wrench socket as at |35.

An indexing plate |40 is rotatably mounted upon the arm |30. This indexing plate |40 consists of a cylindrical supporting member |4| which has a reduced end portion |42 extending through a split bearing |43 positioned upon the arm |30. The ball thrust bearing |43a is positioned between the cylindrical member |4| and the arm |30 and is carried upon the shoulder formed by the reduced end portion 42. This thrust bearing |43a assumes frictional resistance when the indexing plate |40 is to he rotated after a workpiece has been clamped within the chuck |25 in a manner hereafter described.

The upper end of the reduced end portion |42 is provided with a collar |10 which is secured thereto by means of the pins |1|. The collar |10 engages the upper face of the split bearing |43 and retains the cylindrical supporting member |4| in position upon the arm |30. Also, this upper end portion |42 of the cylindrical member |4| is provided with a plurality of passageways |43?) which extend radially from the axis of the member |4|. These passageways are adapted to cooperate with a plunger |44 extending from within the arm |30, and which slides within a passage |45 provided in the arm |30. Passageways |4313 and the plunger |44 are accurately dimensioned for retaining the indexing plate |40 within accurate angular displacements about the axis of the indexing plate in the same manner as the arrangement heretofore described with regard to Figure r2.

A gear segment |45` is adapted to cooperate with a gear rack |41 provided upon the plunger |44 to move the same to and f ro within the pas' sage |45. This gear segment |456 is bearinged upon a pin |48' which extends through the arm |30 upon lo'oth sides thereof and has mounted thereon an eccentric M (seeliigure' 110). The eccentrics M9 coopera-te with the arms |50 which are in engagement with the movable portion of the' split bearing |43.

The split bearing I43` consists of a stationary portion I'5I anda movable portion-|52. The st ationary portion I! is attached to the arm |=30 and is provided with flanges |53 extending from opposite sides' thereof through which the arms |150 extend insuitably bored holes: The arms |50y also extend through flangesr |55 provided uponthe movable portion |52 of the spli-tb'earing. A threaded collar |55 and a nut |56 are provided uponthe end of the arms |50 and retain the movable portion |52 of the split bearing |43y upon the arms |50. Suitable anges |57 extend from the arm through which the arms #50- extend. The anges |51 and |53' provide means for guiding the arms |50` in parallel relation so that the movable portion |52l of the split bearing III-3'Y may be caused to engage or di'sengage the reduced end portion P42 of the indexing plate |40.

The eccentric I |19v is positioned within a slot |50 provided within an enlargement |55' provided upon the endsof the arms |50. Since the eccentric |49 and the gear segment |46- are mounted upon theV common shaft |48, itis thus seen that when the gear segment is rotated either manuall-y, or by automatic means, that the eccentric |49 will also be rotated whereby coordination of operation of the plunger |44 and the movable or locking half |352 ofthe split bearing |43 isV produced.

To supporta work element Within the chuck |725 and between the arms |30 and IS'I, theA arm- I'3-I is provided with a rotatably mounted support element |60 which is bearinged within the arm l.

|'3F as at Iii-I.4 i machine screw F62', having an enlarged head |63, is in threaded engagment with the member |501 and retains the same upon the arm |3-I". A ball thrust bearing |64 is positioned between the supporting member |60 and the armA I3 I to assume thrust produced when the arm I3 Iy is moved to causel engagement of the support member adjacent the workpiece 80.

'I'o providea means for properly positioning the workpieceV 90 upon the' indexing plate |45 so that thev passageways |430 will bear the proper relationship with thevarious angular cuts tob'e produced upon the workpiece 00, the pins |65 are secured within the support member I'4`| and are adapted to engagesuitably positioned holeswithin theI workpiece 90.

The operation of the device is such that whenl a workpiece 90' is to beinserted within the chuck |25', the workpiece brought adjacent the supporting members IM and A suitablewrench is inserted within the wrench socket |35 and' the screw |53v rotated, whereby the arms |130` and |3| are advanced toward the workpiece 90 until the supporting members I'4I4 and IBO are in engagement therewith. The pins are alignedy with the suitable holes in the workpiece |10y toJ properly arrange the workpiece upon the indexing plate |40. The screw |33'v is then tightened to rigidly secure the workpiece between the indexing plate and supporting element |40, I4| and the |44 is withdrawn from the passage IIIIiby the Workpiece 9 0 may be readily indexed to its next sucoes` sive position. l

Also, as heretofore mentioned, the movement of the plunger |44 by the gear segment |56 willalso cause movement of the eccentric |40 to cause vthe same to release the arm |50 when theplung'er |44- is retractedfrom the passage H1131)I in the index` ing plate |520,- thereby unlocking the'l indexing plate to permit same to be rotated; Itthus follows that when the plunger re-engages' the passage I43b,fthe eccentric' |49 will assume the position disclosed in Figure 10 to/thereby retract the arm |50 to cause the movable portion v|52 of the split bearing |43 to engage the indexing plate |40 and retain the same from rotation. Collars are provided upon the arms |50 to prevent too" great a movement of the movable portion of the split bearing |52', thereby preventing the work from falling from the chuck when the split bearing i-s released to unlock the same for rotational movement.

It is thus seen that I have provided an indexing device for use upon lathes or other turning machines' which will permit precise' indexing of the angular displacement of the various operations aroundV the circumference of a workpiece and wherein each workpiece applied to the devi-ce shall have the exact same angular displacement of the various turned elements thereof. It is also seen that I have provided a device which will permit removal of a workpiece from the turning machine and replacement thereof in the exact position which it had heretofore assumed on the' machine,

and that through the use of micrometer indicating devicesl working in cooperation withy previously prepared checking surfaces that it is possible' to precisely determine the position ofthe chuck and the workpiece upon the face plate of a turning machine.

While the form and embodiment disclosed in.`

this application show a preferred form, yet it is desirable to cover all forms which fall within the scope of the following claims. v

Having thus fully described .my invention,

E what I claim as new and desire to secure by Letters Patent is:

1. In a work holding chuck, a frame comprising a base` having parallel arms extending therefrom in planar alignment, a work securing means mounted in one 0f the extending arms forfree rotation therein, an indexing plate mounte'din the other arm for free rotation therein and providing va work securing means for cooperation with the first mentioned work securing means, said first work'Y securing means and said indexing plate' providing ya pivotal axis for a work piece positioned therebetween, accurately bored passageways extending radially from the axis of the indexingplate at predetermined angles and in planar *arrangement` an accurately bored passageway' in the indexing plate mounting arm in planar alignment with said radial passages and in longitudinal alignment therewith when successive radial passages are indexed adjacent thereto, a reciprocable plunger slidably engaging said mounting arm passageway, and means to reciprocate said plunger into engagement with said radial passages when indexed adjacent thereto to accurately position the indexing plate upon its rotational axis.

2. In a machine tool, a chuck frame comprising a base having arms extending therefrom in planar alignment, means pivotally positioned on said arms for securing a Work element therebetween in axial alignment with the base, one of said means comprising an indexing plate having a plurality of radially extending passageways therein, a pin slidably mounted within an arm and adjacent said indexing plate, a portion of said pin comprising a gear rack, a gear segment rotatively mounted adjacent said pin and in operative association with said gear rack and means to rotate said gear segment to advance or retract said pin with respect to a passageway in said indexing plate.

3. In a Work holding chuck, a frame comprising a base having arms extending therefrom in planar alignment, a work holding means pivotally positioned on each of said arms, said work holding means being adapted to position a work element in axial alignment with the axis of said base, one of said means comprising an indexing plate, means engaging said indexing plate to axially position the same, and means binding said indexing plate against the support arm for the same for securing said indexing plate against rotation.

4. In a. work holding chuck, a frame comprising a base having arms extending therefrom in planar alignment, a work holding means pivotally positioned on each of said arms, one of said means forming an indexing plate, means engaging said indexing plate to axially position the same, means binding the indexing plate against rotation for rigidly securing said indexing plate in axial position, and means to simultaneously operate said indexing plate engaging means and said binding means to cause binding and unbinding simultaneously with engagement and disengagement respectively.

5. In a Work holding chuck, a frame comprising a base having parallel arms extending therefrom in planar alignment, one of said arms having a semi-circular shaped end portion forming one half of a split bearing, a half bearing forming the cooperating half of the split bearing, an indexing plate pivotally mounted in said split bearing, a work securing means pivotally mounted in the other arm and providing a cooperating work securing element, said work securing means and said indexing plate providing a pivotal axis for a work piece, and means for clamping said split bearing upon said indexing plate to prevent rotation thereof when the chuck is rotated.

6. In a work holding chuck, a frame comprising a base having parallel arms extending therefrom in planar alignment, a work securing means pivotally mounted in one of the extending arms, an indexing head pivotally mounted in the other arm and providing a cooperating work securing element, said head comprising end portions joined by an annular reduced diameter'Y portion which serves as an axle for the indexing head, said work securing means and said indexing head providing a pivotal axis for a work piece, a plurality of accurately bored passageways in one of the end portions of said indexing head,

said passageways extending radially from the axis of said head at predetermined angles and in planar arrangement, an accurately bored passageway in the indexing head mounting arm in planar alignment with said radial passages and in longitudinal alignment therewith when said radial passages are adjacent thereto, a reciprocable plunger slidably positioned within said mounting arm passageway, said plunger having a gear rack associated therewith, and an oscillatable gear in engagement with said rack to reciprocate said plunger into engagement with said radial passages for accurately positioning the indexing plate upon its rotational axis.

7. In a Work holding chuck, a frame comprising a base having arms extending therefrom in planar alignment, means pivotally positioned on said arms for securing a work element therebetween in axial alignment with the base, one of said means comprising an indexing plate mounted within a split bearing carried by one of said arms, means engaging said indexing plate to axially position the same, means for clamping the split bearing upon said plate for rigidly securing said plate to said support arm, and means to simultaneously operate said indexing plate engaging means and said clamping means to cause clamping and unclamping concomitant with engagement and disengagement respectively.

8. In a work holding chuck, a frame comprising a base having arms extending therefrom in planar alignment, means pivotally positioned on said arms for securing a work element therebetween in axial alignment with the base, one of said means comprising an indexing plate mounted within a split bearing carried by one of said arms, a plurality of passageways in said indexing plate arranged radially from the axis thereof and in a common plane, a passageway in said indexing plate support arm in planar alignment with said radial passageways` and in longitudinal alignment therewith when said radial passageways are 'adjacent thereto, a reciprocable plunger slidably engaging said passageway in said support arm, means for clamping said split bearing upon said indexing plate for rigidly securing said plate to said support arm, and means to simultaneously reciprocate said plunger with operation of said clamping means, whereby said plunger engages and disengages said radial passageways concomitant with clamping and unclamping respectively of said bearing.

9. In a work holding chuck, a frame comprising a base having arms extending therefrom in planar alignment, means rotatably mounted in said arms for securing a work piece therebetween on an axis from the axis of rotation of the chuck, one of said means comprising a cylindrical indexing head having a reduced diameter portion, a, split bearing carried by one of said arms, the reduced diameter portion of said indexing head being associated with said split bearing for mounting said head upon said arm, a plurality of passageways extending radially from the axis of said head arranged in a plane through the enlarged portion of said head, plunger means reciprocably mounted in said indexing head support arm arranged for reciprocable association with said radial passageways, and means to reciprocate said plunger with respect said passageways.

HERMAN W. EBERHARDT. 

